1. Field of the Invention
This invention relates to optical lenses and more particularly to the production of glass-plastic composite ophthalmic lenses.
2. Description of the Prior Art
For many years optical lenses were made of glass. Notwithstanding the advantageous properties of glass for such use, glass ophthalmic lenses are heavy, and fragile. In recent years, plastic materials have come into use for the production of optical components. While plastic optical products are less expensive to manufacture and are lighter in weight than glass, they have the disadvantage of low index of refraction and insufficient resistance to scratch. In an effort to eliminate the disadvantages and combine the advantages associated respectively with glass and plastics, the prior art has produced glass-plastic composites for optical and ophthalmic use. Such composites may comprise an optically clear plastic laminated to a glass lens or a plastic lens body may be sandwiched between two glass shields.
The manufacturing of glass-plastic composites is not free of problems associated with the lamination of two components having different physical characteristics.
A major problem in the production of such composites is the occurrence of distortion and wrinkles in the flat plastic disc upon its lamination to the aspherical or toroidal shape glass component of the composite as will be described briefly hereunder.
In a typical procedure of making composites, an inorganic glass, prefinished by grinding and polishing to prescription on both of its major surfaces, is bonded to an organic, optically clear plastic material. The plastic material may be of a single layer or may be a composite of two layers, one of which serves as an adhesive promoting adherence of the plastic material to the glass component of the composite. This plastic material is in the form of individiual flat wafers. The lamination process includes prepositioning the glass over the wafer, applying pressure to the wafer surface using a pressing means such as a plunger designed to allow center to edge spreading of the wafer, and bonding the components together in an autoclave under appropriate temperature and pressure.
It has been found that the application of a plunger to accomplish lamination of the components caused distortions and wrinkles in a large percentage of the composites.
It is the principle object of the present invention to provide an apparatus for producing high quality glass-plastic composite optical products.
It is a further object of the invention to provide a method for producing high quality glass-plastic composite optical products by which a large percentage of loss as rejects is eliminated.